Bicytopenia with haemolysis: Think severe vitamin B12 deficiency-associated thrombotic microangiopathy.

This article focuses on bicytopenia caused by severe Vitamin B12 deficiency presenting as pseudo-thrombotic microangiopathy (pseudo-TMA), a condition that can mimic thrombotic thrombocytopenic purpura (TTP) or microangiopathic hemolytic anemia (MAHA). It highlights the importance of distinguishing pseudo-TMA from true TTP/MAHA to avoid inappropriate treatments such as plasmapheresis or immunomodulation. Key diagnostic tools include measuring Vitamin B12 levels, reticulocyte counts, peripheral blood smear findings (e.g., hypersegmented neutrophils), and ADAMTS13 activity, with the latter being definitive for TTP diagnosis. The article presents a case of a 72-year-old woman with bicytopenia and laboratory evidence of hemolysis due to severe Vitamin B12 deficiency, who improved with Vitamin B12 replacement therapy.